Cutoff Filter

cutting off light. cutting off learning. cutting off experience.

Photography is an experimental studio art — with experiment meaning experience. Art is philosophy — as photographers gain experience they make it and themselves meaningful. We walk around becoming more and more an artist. Maybe our photography, that physical stuff, never catches up to us. Most photographers stop themselves rather than being stopped. I find them, the stalled ones, gather together saying they want to help others. They offer advice which, on face, seems sound, it is often repeated. It is rarely based upon direct experience. It is often wrong — in application and theory.

In the color darkroom — the age of enlargers. When enlargers were called that. No need to give them a new coat calling them “optical” — they were enlargers, the key to the photo-lab, the darkroom was built to house them. They used hot-lights — light bulbs.

Enlarger Lamps

ESJ 3350K … PH140 3000K — two common lamps with their respective color temperature. These are both small bulbs used in small, but common darkroom enlargers. A chart of color temperature may help in understanding why we need IR cutoffs in a hot enlarger.

Chopping the IR off the enlarger light path means the emulsion will have less spurious response to the image being projected (enlarged). Infrared isn’t “heat” — there is a thermodynamic element to it, however, in main the photographic emulsion will respond differently with and without an IR filter in place and filtering the projection light.

For those of you making color separations or color internegatives this will be noticed, it is measurable, for blue and cyan. The horizon colors.

This came up because an on-liner had a problem with color balance — it seemed nothing could be done; that the balance was illogical, showing sporadic response. Many of the often outspoken experts said it must be the failure of the poster — their skills weren’t good for the task. Not the task of doing, not even the task of diagnostic. Several days. Several efforts. The likely answer was pointed out by someone who has little experience printing; this according to themself — having only begun printing in the past three years. They are correct in the diagnosis of the problem while the other, over 10 thousand posters haven’t yet agreed. Experiment can’t convince them. Display can’t convince them.

They can’t see what they didn’t expect.

They have so little experience that they don’t understand, can’t accept yours.

They may be well intentioned — attempting to maintain knowledge from a field of past knowledge, but they are keeping alight a flame they never lit. They never were on that road, the path they say they’re maintaining. The field of casual knowledge wasn’t enough to work in a professional lab then, it certainly isn’t enough to sustain the field now. Experience doesn’t come in teacups


Refs:

https://physics.stackexchange.com/questions/80983/how-does-infrared-relate-to-heat#:~:text=There%20is%20no%20special%20link,radiate%20at%20a%20higher%20frequency.